breather

Breather is a term with several related meanings across everyday language, engineering, and specialized equipment.

In general use, a breather is a person who breathes. The word also refers to a short period of rest or relief from effort, as in taking a breather after work.

In mechanical and industrial contexts, a breather is a vent or opening that allows air to enter or escape a sealed system to equalize pressure and prevent condensation or seal damage.

Common applications include engine crankcases, gearboxes, hydraulic reservoirs, and compressed-air receivers. Breathers are often fitted with filters or desiccants to keep out dust and moisture and may be designed to minimize oil mist or contamination.

In diving and some safety equipment, the term breather may be used informally to describe a breathing apparatus, especially a rebreather, which recycles exhaled gas to extend gas supply. Such systems are complex and require training and certification.

Related terms include breath, ventilation, vent, and rebreather.